It sounds like Airfoil Speakers Touch wasn’t removed for no reason — it was removed for what many developers might consider a bad reason. According to Underscore David Smith:

In order for these apps to simulate an AirPlay receiver they must reverse-engineer the AirPlay protocol. The protocol (outlined here) is cryptographically secured to prevent anyone other than Apple or its approved vendors from using it. Last year James Laird hacked out Apple’s private key from an old Airport Express and published it.

As best I understand the technical details of this, in order for any of these apps to operate they must then make use of this private key to impersonate an Airport Express. It seems entirely reasonable that Apple would not condone the use of their hacked private key in this manner, least of all in an App Store app.

It’s debatable whether this is fair. But, at the very least, Apple’s communication to developers still needs improvement, and it sucks that this app was approved and had been promoted, improved, supported, and maintained by Rogue Amoeba for three months before being pulled by Apple, probably permanently, with only two days’ notice.